Learning pure quantum states (almost) without regret

Fuente: arXiv
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Main Authors: Lumbreras, Josep, Terekhov, Mikhail, Tomamichel, Marco
Format: Preprint
Published: 2024
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author Lumbreras, Josep
Terekhov, Mikhail
Tomamichel, Marco
author_facet Lumbreras, Josep
Terekhov, Mikhail
Tomamichel, Marco
contents We initiate the study of sample-optimal quantum state tomography with minimal disturbance to the samples. Can we efficiently learn a precise description of a quantum state through sequential measurements of samples while at the same time making sure that the post-measurement state of the samples is only minimally perturbed? Defining regret as the cumulative disturbance of all samples, the challenge is to find a balance between the most informative sequence of measurements on the one hand and measurements incurring minimal regret on the other. Here we answer this question for qubit states by exhibiting a protocol that for pure states achieves maximal precision while incurring a regret that grows only polylogarithmically with the number of samples, a scaling that we show to be optimal.
format Preprint
id arxiv_https___arxiv_org_abs_2406_18370
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Learning pure quantum states (almost) without regret
Lumbreras, Josep
Terekhov, Mikhail
Tomamichel, Marco
Quantum Physics
Artificial Intelligence
Machine Learning
We initiate the study of sample-optimal quantum state tomography with minimal disturbance to the samples. Can we efficiently learn a precise description of a quantum state through sequential measurements of samples while at the same time making sure that the post-measurement state of the samples is only minimally perturbed? Defining regret as the cumulative disturbance of all samples, the challenge is to find a balance between the most informative sequence of measurements on the one hand and measurements incurring minimal regret on the other. Here we answer this question for qubit states by exhibiting a protocol that for pure states achieves maximal precision while incurring a regret that grows only polylogarithmically with the number of samples, a scaling that we show to be optimal.
title Learning pure quantum states (almost) without regret
topic Quantum Physics
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2406.18370